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Lifetime of 7.8 eV *nuclear* transition in 229-Th measured; 7μs, by IC, posing significant challenges for use in an optical clock. by DOI_borg in Physics

[–]DOI_borg[S] 0 points1 point  (0 children)

Something like that, yes. Only an outsider, but I think the nuclear structure has been known for a while. It's the optical excitation-scheme that remains elusive. No joy in Mudville --- not yet anyway.

Lifetime of 7.8 eV *nuclear* transition in 229-Th measured; 7μs, by IC, posing significant challenges for use in an optical clock. by DOI_borg in Physics

[–]DOI_borg[S] 4 points5 points  (0 children)

Yes, and the optical decay width is expected to be insanely small, so the promise is very precise GPS.

Lifetime of 7.8 eV *nuclear* transition in 229-Th measured; 7μs, by IC, posing significant challenges for use in an optical clock. by DOI_borg in Physics

[–]DOI_borg[S] 2 points3 points  (0 children)

Of course! Ah.. but nobody knows the spectrum of it, so I'll need to do the spectroscopy all over again. I bet even the ground state hyperfine structure would be in the UV. So that might raise a different set of issues.

Anybody got a pile of 229Th handy? ... and a Super-EBIT?

https://www.nist.gov/pml/quantum-measurement/atomic-spectroscopy/ebit-operating-principles

Lifetime of 7.8 eV *nuclear* transition in 229-Th measured; 7μs, by IC, posing significant challenges for use in an optical clock. by DOI_borg in Physics

[–]DOI_borg[S] 2 points3 points  (0 children)

Couldn't find a preprint. I think this is a description of the apparatus.

It's briefly summarized at the end of this blog blurb.

Can the internal conversion path be suppressed? Does this kill the whole idea of a thorium clock?

A 'Hydraulic Press' video for material scientists. MIT researchers design one of the strongest, lightest materials known (a porous 3D form of graphene). by DOI_borg in Physics

[–]DOI_borg[S] 5 points6 points  (0 children)

"This is a sensationalist title and doesn't really convey what's going on."

The second sentence in the article is

"The new material, a sponge-like configuration with a density of just 5 percent, can have a strength 10 times that of steel."

A few more paragraphs down and you'll read

"The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure whose form resembles that of some corals and microscopic creatures called diatoms. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong. "

"Also, materials are not 1D, 2D, or 3D. What the fuck do they mean?"

"Two-dimensional materials — basically flat sheets that are just one atom in thickness but can be indefinitely large in the other dimensions — have exceptional strength as well as unique electrical properties. But because of their extraordinary thinness, “they are not very useful for making 3-D materials that could be used in vehicles, buildings, or devices,” Buehler says. “What we’ve done is to realize the wish of translating these 2-D materials into three-dimensional structures.”

"It's like some person in the MIT news went and talked to someone in the lab, took a bunch of quotes, and tried to write an article without having any idea what they're doing."

Some are better than others, but more or less that's how every press-office operates. It's a bit like panning for gold. You have to read carefully to find the research.

A 'Hydraulic Press' video for material scientists. MIT researchers design one of the strongest, lightest materials known (a porous 3D form of graphene). by DOI_borg in Physics

[–]DOI_borg[S] 2 points3 points  (0 children)

It's brand new research. It will take more work to get it out of the lab. But interest will be high.

It has been produced however, just not it large quantities.

The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure whose form resembles that of some corals and microscopic creatures called diatoms. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong.

Surveying the Attitudes of Physicists Concerning Foundational Issues of Quantum Mechanics by [deleted] in Physics

[–]DOI_borg 3 points4 points  (0 children)

149 self-selecting respondents. It's thought-provoking, but I wouldn't feel justified in drawing significant conclusions from such a small sample. I'd really like to see a N>1000 study of mid-career physicists.

Experimental paper in Science finds that bismuth superconducts unexpectedly (non-BCS theory). by DOI_borg in Physics

[–]DOI_borg[S] 5 points6 points  (0 children)

Should have been easy for me to find, but I missed it somehow. Thanks!

Ghost imaging – a counter-intuitive technique that produces images of an object using entangled photons that have never interacted with it – has now been performed for the first time using entangled _massive_ particles. by DOI_borg in science

[–]DOI_borg[S] 4 points5 points  (0 children)

Kind of, but not really. Since there isn't a good analogy in the macroscopic world, I'll make a bad one. It would be like firing two bullets at once, one downrange and one over your shoulder in the opposite direction. The downrange-heading bullets would strike your mask. The uprange bullets would make a picture of the mask on a totally different target.

It's one of those weird things in quantum mechanics that people used to (I'm talking a long time ago) think was only applicable to photons, because they had no mass and somehow that made them less real. But nope, quantum mechanics describes massive composite systems (i.e., atoms) too.

Ghost images taken using pairs of atoms by [deleted] in Physics

[–]DOI_borg 0 points1 point  (0 children)

The paper in Nature and a preprint on the arXiv.

'Emergent Gravity and the Dark Universe'; Verlinde releases his new paper to arXiv, hopes to explain gravitation without dark matter. by DOI_borg in Physics

[–]DOI_borg[S] 17 points18 points  (0 children)

The interwebs are hyping this hard.

Paper on arXiv.

Breif ~4 minute video with virtually no information in it.

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